Various techniques for high frequency applications have been known, as disclosed, for example, in Japanese Laid-Open Patent Publication Nos. 8-139107 (1996), 6-61365 (1994), and 1-273404 (1989).
In high frequency applications, the electrical characteristics of the semiconductor devices are significantly affected by their operating frequency, which may cause various problems. In order to address such problems, different techniques have been studied, including those disclosed in the above three publications. Specifically, the first publication discloses a semiconductor device package construction, the second publication discloses a semiconductor chip mounting method, and the third publication discloses the construction of a high frequency circuit including matching circuits.
High frequency semiconductor devices are generally mounted on mounting circuit substrates when used in practical applications. Each portion of a mounting circuit substrate (e.g., wiring patterns) usually has a configuration determined in accordance with the specifications of the semiconductor device to be mounted on the substrate.
A problem associated with high frequency semiconductor devices is that the power gain decreases as the operating frequency increases. In this connection, the present inventor has found that there is still room for improvement in the construction of mounting circuit substrates to improve the high frequency characteristics of the semiconductor device mounted thereon.